Pleurocryptella altalis, Williams & Boyko & Marin, 2020

Williams, Jason D., Boyko, Christopher B. & Marin, Ivan N., 2020, A new species and depth record of bopyrid (Crustacea, Isopoda) from a squat lobster in the Kuril-Kamchatka Trench, European Journal of Taxonomy 724, pp. 122-133 : 124-127

Pleurocryptella altalis sp. nov.

urn:lsid:zoobank.org:act:65006984-C3F1-4C31-ABEF-8225A15F921E

Figs 1–3

“C параЗИтИческой ИЗоподой под карапаксом” – Birstein & Zarenkov 1970: 423, fig. 1.

“parasitic isopod” – Birstein & Zarenkov 1972: 442, fig. 1.

“bopyrid parasite” – Boyko et al. 2012: 25, table 1. — Marin 2020: 2, figs 1a, 17f.

Etymology

Combination of Latin words ‘ altum ’ (‘deep’) and ‘ alis ’ (‘pertaining to’) in reference to its occurrence at the greatest depth known for any bopyrid species.

Type material

Holotype KURIL-KAMCHATKA TRENCH • ♀ (10.4 mm TL) from right branchial chamber of ♂ Munidopsis petalorhyncha Baba, 2005 (21.0 mm CL, 15 mm CW, ZMMU Ma 3504); 39 th cruise of R/V ‘ Vityaz ’, stn 5621, Sigsbee trawl; 45°18′ N, 156°00′ E; depth 5060–5130 m; 17 Aug. 1966; ZMMU Mс 1420 .

Allotype KURIL-KAMCHATKA TRENCH • 1 ♂ (4.3 mm TL); same collection data as for holotype; ZMMU Mс 1421 .

Description

Female ( Figs 1B , 2 )

Body length 10.4 mm, maximum width 6.8 mm across pereomere 3, head length 1.9 mm, head width 3.0 mm. Body ovoid, pereon very slightly deflexed dextrally ( Figs 1B , 2A ), all body regions and pereomeres distinctly segmented. Head subrectangular, broader than long, with frontal lamina extending beyond pereomere 1 and rounded extensions laterally ( Fig. 2A ), eyes lacking. Barbula with two long, thin, tapering lateral lobes, subequal in length ( Fig. 2C ).Antennules of three articles each, terminal article minute, setose; antennae of five articles each, terminal article setose ( Fig. 2D ). Maxilliped ( Fig. 2E ) with minute setae, most prominent on distal margin, short subacute spur; segmented subcylindrical palp present, with stout setae. Oostegite 1 ( Fig. 2 F–G) proximal lobe ovate, distal lobe approximately 50% narrower than proximal lobe, internal ridge smooth ( Fig. 2G ).

Pereon of seven pereomeres ( Fig. 2A ), broadest across pereomere 3, gradually tapering anteriorly and posteriorly; pereomere 1 with convex posterior margin corresponding with posterior margin of head; pereomeres 2–4 straight, pereomeres 5–7 wavy, with progressively greater median concavity and crenulate margins ( Fig. 2A ). Coxal plates and dorsolateral bosses on pereomeres 1–5 ( Fig. 2A ), pereomeres 2–3 with weakly produced tergal projections on right side ( Fig. 2A ). Oostegites incompletely enclosing marsupium ( Fig. 2B ), last two pairs of oostegites reduced, plate-like, with setae on margins ( Fig. 2L ). Pereopods subequal ( Fig. 2 F–K), with small dactyli and broad bases, setae on all articles except bases; first pair at sides of head, others evenly spaced.

Pleon with six pleomeres including pleotelson ( Fig. 2B, M ). Pleomeres 1–4 with biramous, digitiform pleopods, appearing as two stacked articles; pleomere 5 with uniramous, irregularly shaped pleopods; uropods ( Fig. 2M ) uniramous, tapering distally, directed distolaterally, extending just beyond anal cone.

Male ( Figs 1 B–C, 3)

Length 4.3 mm, maximum width 1.7 mm, head length 0.5 mm, head width 1.3 mm, pleon length 1.2 mm. Head hemispherical, widest at posterior margin, distinct from pereomere 1 ( Figs 1 B–C, 3A–B), eyes lacking. Antennules of three articles each, terminal article setose ( Fig. 3C ); antennae of five articles each, basal three articles with rounded extensions, distal three articles setose ( Fig. 3D ). Maxilliped bisegmented ( Fig. 3E ), basal segments small, subrectangular, distal segment elongate with two short, stout setae and four longer, thinner setae on distal end.

Pereomere 4 broadest, others tapering slightly anteriorly and posteriorly ( Figs 1 B–C, 3A–B). Pereomeres 1–4 approximately straight, pereomeres 5–7 directed posterolaterally, distolateral margins of all pereomeres rounded. Pereopods 1 and 2 ( Fig. 3A, F ) each with long, curved dactylus extending to carpus; propodus large, broad; carpus and merus small, rounded; ischium and basis elongate; all articles, except dactylus and basis, with small setae. Pereopods 3–7 ( Fig. 3A , G–H) subequal, all with shorter dactyli than pereopods 1 and 2, other articles similar to pereopods 1 and 2, bases with slight distal bulge.

Pleon ( Figs 1C , 3A, I ) of six pleomeres, pleomeres 5–6 curved anteriorly, sides of all pereomeres curled ventrally and overlapping. Broad midventral tubercles on pleomeres 1–4, reduced one on pleomere 5 ( Fig. 3A, I ), small, low, rounded pleopods on pleomeres 1–5, mostly obscured by curled lateral margins of pleomeres ( Fig. 3I ). Pleotelson bearing articulated, triangular-shaped uropods ( Fig. 3A, I ) extending beyond anal cone.

Note on host identification

The host was originally identified as the holotype of Munidopsis subsquamosa latimana Birstein & Zarenkov, 1970 , but, because that name is a junior homonym of M. latimana Miyake & Baba, 1966 , Baba (2005) proposed the replacement name M. petalorhyncha Baba, 2005 .

Remarks

The new species appears most closely related to Pleurocryptella formosa and P. wolffi . Males of these three species all have low, broad midventral tubercles on pleomeres 1–4 that cover nearly all of the space between the pleopods, whereas males of all other species in the genus have small, semispherical tubercles on the pleomeres that do not cover the space between the pleopods. Both sexes of Pleurocryptella altalis sp. nov. are distinguishable from those of P. formosa and P. wolffi . Males of P. altalis sp. nov. have the lateral margins of the pleomeres curled laterally and covering the pleopods in ventral view (also curled in P. wolffi , but splayed laterally and pleopods visible in ventral view in P. formosa ), the head nearly as broad as pleomere 1 (also as broad in P. wolffi but much narrower than pleomere 1 in P. formosa ), and the uropods larger than pleopod 5 (uropods smaller than pleopod 5 in P. wolffi and the same size as pleopod 5 in P. formosa ). Females of P. altalis sp. nov. have the barbula with two acute, slender lobes of approximately the same length (barbula with outer lobe tapered but much broader, inner lobe much shorter than outer and rounded in P. wolffi and P. formosa ), pleopod 5 less than half as large as pleopod 4 and uniramous (pleopod 5 more than half as large as pleopod 4 and biramous in P. wolffi and P. formosa ), and pleomeres smoothly curved with pleomere 5 not surrounding pleotelson (pleomeres smoothly curved, but surrounding pleotelson in P. wolffi and not smoothly curved (angular middle portion) and not surrounding pleotelson in P. formosa ).

Figures

Fig. 1. Micrographs of Pleurocryptella altalis sp. nov. and host Munidopsis petalorhyncha Baba, 2005 (ZMMU Ma 3504). A. Munidopsis petalorhyncha, ♂, with swelled right branchial chamber from Pleurocryptella altalis sp. nov. B. Pleurocryptella altalis sp. nov., holotype, ♀, dorsal view (ZMMU Mc 1420) with attached allotype, ♂ (ZMMU Mc 1421). C. Pleurocryptella altalis sp. nov., allotype, ♂, oblique ventral view (ZMMU Mc 1421).

Fig. 2. Pleurocryptella altalis sp. nov., holotype, ♀ (ZMMU Mc 1420). A. Dorsal view. B. Ventral view. C. Left barbula. D. Right antennule and antenna. E. Left maxilliped, external view. F. Left oostegite 1, external view with pereopod 1 attached. G. Left oostegite 1, internal view. H–I. Left pereopod 1, lateral view. J–K. Left pereopod 7, lateral view. L. Left pereopod 7 and oostegite, lateral view. M. Pleon, ventral view.

Fig. 3. Pleurocryptella altalis sp. nov., allotype, ♂ (ZMMU Mc 1421). A. Ventral view. B. Dorsal view. C. Right antennule. D. Right antenna. E. Right maxilliped. F. Right pereopod 1, lateral view. G–H. Left pereopod 7, lateral view. I. Pleon, ventral view (pleopods shown in dashed lines).